[raybbr]

Coordinates from the bottle saved them. Their cellphone didn't have the GPS feature. Using both, they were able to tell their rescuers EXACTLY where they were.

I doubt very much that their cell phones don't have GPS on a 911 call. I don't think they even sell them without it anymore.

The GPS he's referring to is a seperate unit the climbers can rent or borrow.

My question still hasnt' been answered.

[ikka]

I doubt very much that their cell phones don't have GPS on a 911 call. I don't think they even sell them without it anymore.

OK, I will have a stab at it.

Cell-phone based geolocation uses triangulation based on the cell phone being able to be seen by more than one cell tower. They are accurate in places like a city, to within 50 or 100 feet.

In such a remote area, there would not be the overlap of cell towers needed to triangulate the position. GPS is a different beast, uses satellites in orbit, and is accurate down to about 3 feet or less.

[Captain Rhino]

No, you can get something like an approximate triangulation on a cell phone’s location by analyzing the arrival time of signals at cell phone towers in the area PROVIDED there is more than one. With two, the fix is not so good. Three or more will give you an approximate location. The location is only approximate since the difference between the signal arrival times can only be measured so precisely (we’re talking of differences in the hundredth of a second or less here) and there is atmospheric distortion to signal travel times that has to be considered as well. This may seem like GPS but it is not even close to its precision. Further, while there are obviously cell phone relay towers in the area (that how the calls went back and forth), they are probably somewhat dispersed due to the terrain and there may not have been enough towers or the overlapping coverage areas needed to do the triangulation as described above.

A cellphone doesn’t have a GPS receiver (for picking up location signals from GPS satellites) unless it is specifically built into the telephone. Adding GPS usually adds significantly to the cellphone’s cost. Further, a GPS receiver doesn't emit a signal (to triangulate on), it just receives ones that are already in the air and computes its location using timing differences from the multiple satellites it “sees” overhead. GPS is superior to the cellphone triangulation method because the likelihood of getting three or more GPS satellite signals is very high due to the extensive coverage in geosynchronous orbits around the Earth and because the calculation algorithm used in determining location is fairly precise.

Pitt said their cellphones didn’t have the GPS capability. Since he was one of the two lost hikers, maybe you should believe him.